Downhole jetting tools have been used for decades to clean debris along the wellbore, including debris in components positioned along the well, such as hydraulic rams and annular blowout preventers (BOPs). The jetting force of the high pressure fluid passing through the central bore in the tool washes debris from the side of the wellbore or from the interior of tools along the wellbore, and the dislodged material then can be returned to the surface and the fluid cleaned and reused. By reliably cleaning a wellbore, efficient drilling and the recovery of hydrocarbons is enhanced. The reliability of downhole components, such as hydraulic rams, annular blowout preventers and wear bushings, is also increased by cleaning debris from pockets within the tool which, if filled with debris, may cause equipment malfunctions. Cleaning tools are particularly useful in applications where metal shot is used to assist in drilling through hard formations, since the metal shot may become lodged in cavities within the downhole equipment, and the equipment may then not function properly.
One example of a downhole jetting tool is Bilco Tool's Wellhead Jet Tool, which includes jets to clean subsea annular blowout preventers. This tool is not capable, however, of effectively cleaning annular BOP's with a large diameter bore positioned above a wellhead with a drilling wear bushing therein having a reduced diameter bore. Another type of jet tool essentially utilizes an upper jet tool similar to the Bilco Wellhead Jet Tool, and a lower jet tool with a reduced diameter intended for positioning within wellhead. The two tools are connected by threaded components, which involve significant cost in reliably maintaining and testing the threaded connections for different runs or jobs. These threaded connections detract from the overall strength of the tool if the tool gets stuck in the well, since separation of the upper and lower tools will likely occur at the threaded connection. Moreover, this combined tool is not reliably positioned in the well with respect to the downhole equipment to be cleaned, and accordingly more time and effort is commonly used to repeatedly raise, lower, and rotate the combined tool with the hope that the critical cavities will be effectively cleaned by the jets.
The disadvantages of the prior art are overcome by the present invention, an improved downhole jet tool is hereinafter disclosed.